Have you recently updated to 2.3 ? The reason I ask is that my friends got the 2.3 update recently & the battery started draining rapidly eventhough there were no apps running in the background & Data,GPS,bluetooth & wifi switched off.

I found this item which helps me a lot when my battery runs out. It charges my phone at least 4 times which is amazing!
It called Portable Phone Charger which could charge my phone anywhere, anytime
I got it from Epower Electronics which I would recommend